H2 receptor-mediated positive inotropic effect of histamine in neonatal guinea-pig left atria

Abstract

The receptor type mediating the positive inotropic effect of histamine was examined in left atria from neonatal guinea pigs. The positive inotropic effect of histamine, as well as its action potential prolonging effect, was antagonized by ranitidine, but not by chlorpheniramine or thiperamide. The positive inotropic effect was enhanced by isobutylmethylxantine. Receptor binding studies revealed the presence of both H1 and H2 receptor types. These results suggest that the positive inotropic effect of histamine in the neonatal guinea-pig atrium is mediated by H2 receptors. © 2010 Pharmaceutical Society of Japan.